China
Africa
Explore chapters and articles related to this topic
Pathogenicity and Virulence
Published in Julius P. Kreier, Infection, Resistance, and Immunity, 2022
Diphtheria toxin, an example of an A-B toxin, is produced by C. diphtheriae. The toxin is a single-chain polypeptide which catalyzes the transfer of adenine diphosphate dinucleotide from nicotinamide dinucleotide to elongation factor 2, resulting in inhibition of protein synthesis. Diphtheria formerly caused very high morbidity and mortality among young children, but since the incorporation of diphtheria toxoid into the Diphtheria-Pertussis-Tetanus (DPT) vaccine the incidence of this disease has been drastically reduced. Other A-B toxins include Shiga toxin of S. dysenteriae, exotoxin A of P. aeruginosa, tetanus toxin of C. tetani, and botulinum toxin of C. botulinum.
Battlefield Chemical Inhalation Injury
Published in Jacob Loke, Pathophysiology and Treatment of Inhalation Injuries, 2020
Staphylococcal cultures may produce a number of biologically active compounds that include one or more enterotoxins. Four distinct antigenic groups of enterotoxins are described (A, B, C, D). These enterotoxins are simple proteins, of which the type B toxin has been most extensively studied (Wagman et al., 1965; Lamanna and Carr, 1967).
Bacteria Causing Gastrointestinal Infections
Published in K. Balamurugan, U. Prithika, Pocket Guide to Bacterial Infections, 2019
B. Vinoth, M. Krishna Raja, B. Agieshkumar
Alpha toxin is produced by type A strain and present frequently in humans. Zinc activates the toxin after which it interacts with the host cell receptors, and through a series of pathways, the permeability in blood vessels is increased and blood supply is reduced to tissues. Beta toxin is lethal and produced by type B and type C strains. Necrotizing enteritis (enteritis necroticans or pigbel), which is rare, is caused by toxins of type C strains and is often obtained by ingestion of undercooked pork. Epsilon toxin is most commonly isolated from animals. which are produced by type B and type D strains. Potassium ions and fluid leakage occurs due to perforation in tissues. Iota toxin, known as AB toxin, is produced by type E strain. B component interacts with the host cell surface receptor to facilitate the uptake of the toxin, while A component inhibits actin polymerization, thereby breaking down the cytoskeleton. Bacteremia and clostridial sepsis is uncommon, but both are fatal occurring with an infection of the uterus, colon, or biliary tract.
Strategies to prevent adverse outcomes following Clostridioides difficile infection in the elderly
Published in Expert Review of Anti-infective Therapy, 2020
Adriana M Rauseo, Margaret A Olsen, Kimberly A Reske, Erik R Dubberke
The second line of defense against CDI is the immune system, in particular, a neutralizing antibody response against C. difficile toxins. C. difficile causes disease through production of two exotoxins, A and B. Toxin B is thought to be the primary toxin involved in the pathogenesis of CDI based on animal models using strains of C. difficile that have had toxin genes knocked out [35,36]. The toxin B mechanism of action is to bind to and enter intestinal cells, resulting in disruption of the cytoskeletal structure and cell death [37]. After intestinal cell death, the toxins induce an acute inflammatory response when they come in contact with the submucosa, characterized by an intense neutrophilic response which can lead to characteristic pseudomembrane formation. The efficacy of the monoclonal antibody against toxin B, bezlotoxumab, in prevention of recurrent CDI both supports the primary role of toxin B and the importance of toxin neutralizing antibodies in the pathogenesis of CDI. Secondary analyses of the bezlotoxumab phase 2 and 3 trials found that persons in the placebo arms with higher levels of anti-toxin B antibodies had decreased risk of recurrent CDI; however, there was no association between recurrent disease and anti-toxin A antibody levels [38,39]. Additionally, the phase 3 trial data found no benefit of actoxumab, a monoclonal anti-toxin A antibody, for the prevention of recurrent CDI, given either by itself or in addition to bezlotoxumab [40].
Foodborne botulism in Turkey, 1983 to 2017
Published in Infectious Diseases, 2019
Hasan Karsen, Mehmet Resat Ceylan, Hasan Bayındır, Hayrettin Akdeniz
The Italian incidence rate is one of the highest in Europe and the largest peak in cases was observed in 1996 in Italy as a consequence of four outbreaks due to commercial foods (mascarpone cheese and olives), and in 2013 as a consequence of a suspected outbreak due to commercial pesto sauce. Type B toxin was implicated in 79.1% of all confirmed incidents, followed by type A, and type F. A total of 80.5% of food items linked to confirmed incidents consisted of home-canned food, while the remaining 19.5% was commercial food. Only one outbreak was connected to restaurant-canned green olives. Vegetables—mushrooms, olives, and turnip tops—canned in oil, home bottled tuna, home bottled meat, salami/sausages, cheese and tofu and seitan were related foods responsible for botulism cases in Italy [10].
Single-molecule measurements in microwells for clinical applications
Published in Critical Reviews in Clinical Laboratory Sciences, 2020
Connie Wu, Adam M. Maley, David R. Walt
Simoa has been demonstrated as a potential diagnostic tool in Clostridium difficile infection (CDI). Because current immunoassays for detecting C. difficile toxins have poor sensitivity, Banz and coworkers used Simoa to measure C. difficile A and B toxins in human stool samples from patients who were either CDI positive or CDI negative (240 total), with LODs of 0.6 and 2.9 ng/L for toxins A and B, respectively [101]. Of the 240 patients, 66 were diagnosed as CDI positive by cell cytotoxicity neutralizing assay. Importantly, the Simoa assays for toxins A and B were able to identify 63/66 patients as CDI positive, whereas the standard immunoassay could identify only 47/66 as CDI positive.